Irradiation damage and mechanical properties in Fe-Au and Fe-Cu model alloys under helium ion irradiation

Abstract

High purity Fe-Au and Fe-Cu alloys were irradiated with He+ ions at a high temperature of 550 °C to simulate service in a nuclear reactor. The radiation swelling and surface damage were characterized and the correlation between Cu/Au precipitates and radiation damage was clarified by the microstructure analysis. Using the nanoindentation technique, the evolution of the mechanical properties with irradiation was investigated. The low radiation swelling and the absence of pinholes and hillock on the surface indicates superior radiation resistance for the Fe-Au compared to the Fe-Cu. The irradiation hardening effect was observed in the Fe-Au while negligible hardening was indicated in the Fe-Cu. The improved radiation resistance arises from preferential Au precipitation at the radiation damage sites, resulting in the self-healing whereas the Cu precipitation and radiation damage are weakly inter-related. The interaction of solute atoms with vacancies and helium may play a key role in the hardness variation during irradiation.